Black holes merging (IMAGE) Xi'an Jiaotong-Liverpool University Caption This illustration shows a stage in the merger of two galaxies that forms a single galaxy with two centrally located supermassive black holes surrounded by disks of hot gas. The black holes orbit each other for hundreds of millions of years before they merge to form a single supermassive black hole that sends out intense gravitational waves. Credit NASA/CXC/A.Hobart, Public domain, via Wikimedia Commons Usage Restrictions No restrictions. License Public Domain Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.